EP4212488A1 - Procédé et préforme pour la fabrication d'une fibre multicoeurs - Google Patents

Procédé et préforme pour la fabrication d'une fibre multicoeurs Download PDF

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Publication number
EP4212488A1
EP4212488A1 EP22151954.9A EP22151954A EP4212488A1 EP 4212488 A1 EP4212488 A1 EP 4212488A1 EP 22151954 A EP22151954 A EP 22151954A EP 4212488 A1 EP4212488 A1 EP 4212488A1
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EP
European Patent Office
Prior art keywords
glass
cylinder
core
marker
cladding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP22151954.9A
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German (de)
English (en)
Inventor
Michael Dr. Lorenz
Kay Dr. Schuster
Tobias Dr. Tiess
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heraeus Quarzglas GmbH and Co KG
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Heraeus Quarzglas GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Heraeus Quarzglas GmbH and Co KG filed Critical Heraeus Quarzglas GmbH and Co KG
Priority to EP22151954.9A priority Critical patent/EP4212488A1/fr
Priority to PCT/EP2023/050959 priority patent/WO2023139049A1/fr
Publication of EP4212488A1 publication Critical patent/EP4212488A1/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
    • C03B37/01222—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube for making preforms of multiple core optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
    • C03B37/01228—Removal of preform material
    • C03B37/01231—Removal of preform material to form a longitudinal hole, e.g. by drilling
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
    • C03B37/01228—Removal of preform material
    • C03B37/01234—Removal of preform material to form longitudinal grooves, e.g. by chamfering

Definitions

  • the invention also relates to a semi-finished product for the production of a multi-core fiber, with a cladding glass cylinder having a longitudinal axis and an outer lateral surface, which has a cladding glass area made of cladding glass, in which several openings for receiving core rods made of a core glass are contained.
  • multi-core fibers In the case of multi-core fibers, a number of light wave-guiding, optical core areas (also referred to below as “signal cores”) are integrated in a common fiber.
  • the signal cores extend along the longitudinal axis of the fiber. They are surrounded by cladding material with a lower refractive index and enable the light to be guided essentially independently of one another.
  • This fiber design promises a high signal transmission capacity, because different signals can be combined in a single optical fiber and transmitted simultaneously in each of the spatially separated signal cores.
  • This method of signal transmission is also referred to as “spatial multiplexing", which can increase the data transmission capacity in optical telecommunications in particular.
  • Multi-core fibers are also considered key components for the transmission of Energy for material processing, as a component of fiber optic sensors in measurement and medical technology, and for lighting and imaging purposes in microscopic or endoscopic devices.
  • Multicore fibers are created by elongating a solid preform or ensemble of components. These often consist of synthetically produced quartz glass (SiO 2 ), which can be doped or undoped.
  • the production of synthetic quartz glass includes, for example, plasma or CVD deposition methods, which are known under the designations OVD, VAD, MCVD, PCVD or FCVD methods.
  • a liquid or gaseous silicon-containing starting substance is subjected to a chemical reaction (hydrolysis, pyrolysis or oxidation) and the reaction product - particulate SiO 2 - is deposited as a solid from the gas phase on a deposition surface.
  • the starting substance is, for example, silicon tetrachloride (SiCl 4 ) or a chlorine-free silicon compound such as a polyalkylsiloxane.
  • the reaction zone is, for example, a burner flame, an arc (plasma) or a furnace.
  • core rods and glass cylinders of different diameters are stacked together in such a way that they result in a relatively high packing density and a certain symmetry.
  • the cylindrical components are inserted into a cladding tube and spatially fixed therein.
  • This ensemble is drawn into the multi-core fiber or it is further processed in advance into a preform from which the multi-core fiber is then drawn.
  • the "stack-and-draw method" requires a lot of adjustment effort and it easily leads to dimensional errors and the entry of contamination due to the large proportion of free component surfaces.
  • the elongated preform often has different radius values in the azimuthal direction, which must be compensated for by cylindrical grinding.
  • the separation mandrel is removed so that a central passage opening remains in the central axis of the cylindrical soot body.
  • Longitudinal bores for receiving core glass rods are made in the cladding glass hollow cylinder produced in this way, with the lower density of the SiO 2 soot body compared to quartz glass facilitating the production of dimensionally accurate longitudinal bores.
  • the remaining central "OVD through-opening" caused by production can lead to asymmetrical deformations when collapsing and destroy the fiber design.
  • the cross-sectional area of the cladding glass portion is reduced as a result of the collapsing.
  • the filler rod is made of glass that has essentially the same refractive index as the cladding glass hollow cylinder.
  • the filler rod can also be made by an OVD process or by compression molding or by a combination of compression molding and OVD processes.
  • a channel for accommodating a marker element is introduced into the cladding glass hollow cylinder. The channel is created by mechanical drilling in the area near the edge of the cladding glass hollow cylinder.
  • the marker elements form continuous, line-like marker zones in the multi-core fiber and serve to break the symmetry in order to clearly identify the signal cores and their positions in relation to one another and in relation to the central axis of the fiber and to be able to clearly allocate them to one another. This is necessary, for example, so that two multi-core fibers can be joined together at their end faces using conventional splicing methods with little loss.
  • the fiber ends to be connected are arranged in such a way that their end faces face each other.
  • light is fed into all signal cores at the opposite end of the fiber at the same time, and at the fiber end of the other multi-core fiber collectively by means of Photo detector and power meter detected.
  • this multi-core fiber is irradiated laterally with light.
  • the fiber ends are automatically aligned with each other in a fusion splicing machine until the signal cores are correctly assigned to each other and the collective received light power is maximum and then in this position with each other merged.
  • This splicing method assumes that the multi-core fiber is spliced in advance - for example, in a factory.
  • the U.S. 9,541,707 B2 proposes a design of the multi-core fiber in which several signal cores are arranged in a cladding glass region and in which a marking zone is exposed on the outer cladding surface of the multi-core fiber.
  • the special characteristic of this fiber design is also referred to below as the “marker zone near the edge”.
  • a large number of through-holes are produced in a cladding glass cylinder, which run in the direction of the longitudinal axis of the cylinder. Namely several core rod holes and a marker rod hole.
  • the marker rod hole is as close as possible to the outer surface of the jacketed glass cylinder.
  • a core rod is inserted into each core rod hole and a marker rod into the marker rod hole. Then the outer circumference of the jacketed glass cylinder is ground down until part of the marker rod is exposed.
  • the multi-core fiber is pulled from the component ensemble prepared in this way, on the surface of which the marker zone is exposed.
  • the cladding glass cylinder is elongated.
  • the through-holes therefore have a large aspect ratio (ratio of length and diameter), which fundamentally complicates their dimensionally accurate manufacture and exact alignment parallel to the longitudinal axis of the cladding glass cylinder.
  • each of the multi-cores has an optical attenuation approximately equivalent to that of a single-core optical fiber.
  • This requires that the fiber design does not introduce additional attenuation or interfere with the signal cores' independent information transmission as a spurious signal.
  • this can be caused by so-called "crosstalk" between the multiple cores, in particular if they are too close together. This effect therefore requires compliance with a certain minimum distance between the fiber cores. For these reasons, there is a need to use the cross-sectional area available in the radial cross section of the multi-core fiber as completely as possible for covering with the multi-cores.
  • marker zones are always imperfections in the multi-core fiber, which should always be as small as possible but as large as necessary to ensure their detectability.
  • a small size of the marker zones is also advantageous in order to counteract other undesired effects, such as the so-called fiber curl or stresses induced in the fiber.
  • the additional marker zones to be added to the fiber design should therefore occupy as small a proportion of the fiber cross-section as possible.
  • the diameter of the channel for accommodating the marker element is therefore small and generally significantly smaller than the diameter of the bores for accommodating the core rods.
  • the channel diameter in the cladding glass cylinder before the fiber drawing process is less than 15mm, along with an aspect ratio above 65 (with a cylinder length of around 1m).
  • An additional difficulty with the marker rod hole near the edge is that only a thin residual wall remains, which can easily break both during the production of the through hole and during further processing, especially when inserting the marker rod.
  • the invention is therefore based on the object of specifying a method for producing multi-core fibers with a marker zone near the edge, in which the risk of rejects is reduced.
  • the invention is based on the object of providing a semi-finished product that is suitable for carrying out the method.
  • this object is achieved according to the invention, based on the method mentioned at the outset, in that the marker element is arranged on the outer lateral surface of the jacketed glass cylinder.
  • the component ensemble is equipped with a marker element without having to create a separate hole in the jacketed glass cylinder - associated with the risks and difficulties explained above.
  • a high degree of accuracy can be guaranteed, which is manifested, for example, in the preform or in the component ensemble in that the axial parallelism of the marker element has a deviation of less than 0.3 mm/m.
  • the marker element is in the form of a rod which extends parallel to the outer jacket surface of the jacketed glass cylinder.
  • the marker element is present as a layer which is applied in the area of the outer jacket of the jacketed glass cylinder.
  • core rod bores are introduced into the cladding glass cylinder, the longitudinal axes of which run parallel to the longitudinal axis of the central bore.
  • the core rod holes are through holes or blind holes and are used to hold at least one core rod from the core glass.
  • the composition of the core glass is consistently homogeneous as seen in the radial direction, or it changes gradually or in stages. It differs from that of the cladding glass in that light is guided in the core glass area.
  • the desired number of core rod holes is either created in one operation and each covered with at least one core rod. Or only one core rod bore or only a first proportion of the desired number of core rod bores is produced in advance, each of which is occupied by at least one core rod, and the core rod bores occupied by the core rods are collapsed (this forming process is also referred to here as “referred to as "consolidation"), before the remaining part or a further part of the core rod bores is produced in a second or further operation, and this part is also covered with at least one core rod and possibly collapsed.
  • all core rods have the same dimensions and consist of the same core glass. However, the core rods can also differ in their dimensions and/or in the composition of the respective core glass.
  • the marker element can be arranged on the outer lateral surface before or after all core rod bores have been produced and/or filled, or it can take place before or after some of the core rod bores have been produced and/or filled. In a preferred procedure, the marker element is arranged on the outer lateral surface, and then the desired core rod bores are produced.
  • the component ensemble produced in this way is reshaped and either drawn directly into the multi-core fiber or it is consolidated into a preform for the multi-core fiber, in which case the consolidation can be accompanied by simultaneous elongation.
  • the "consolidated preform" thus produced is optionally drawn into the multi-core fiber or is further processed into a "secondary preform".
  • the further processing to the "secondary preform” includes, for example, the production of further bores in the cladding glass area and their covering with core glass or with other glasses or the single or repeated implementation of one or several of the following hot forming processes: collapsing additional cladding material, collapsing, elongating, collapsing and simultaneously elongating.
  • the multi-core fiber is drawn from the secondary preform produced by further processing.
  • Fiber splicing devices can identify the marker zone faster and more accurately. Due to the comparatively simple detectability of the marker zone near the edge, this can be particularly small, so that a comparatively small fiber curl is impressed on the multi-core fiber during the fiber drawing process.
  • Fiber curl is a property of glass fibers that is defined as the degree of bending over a given length of fiber. The curvature results from thermal stresses that arise during fiber manufacture. A high "fiber curl” makes it difficult to splice the multi-core fiber with low loss.
  • a recess extending in the direction of the longitudinal axis of the cylinder is produced in the outer jacket surface of the jacket glass area, in which recess the marker element is arranged.
  • the recess is preferably designed as a longitudinal groove (longitudinal groove) on the outer surface of the jacketed glass cylinder.
  • a longitudinal groove in the outer lateral surface is particularly easy to manufacture compared to a bore; for example by milling with a mechanical milling cutter or by laser ablation.
  • the longitudinal groove created in this way is just as precise and straight as the cladding glass cylinder itself.
  • the depth or the opening width of the longitudinal groove can be kept almost arbitrarily small; for example both less than 15mm, preferably less than 10mm and most preferably less than 5mm.
  • the longitudinal groove is filled with the marker element, for example, by inserting a cylindrical component (rod or tube) made from a marker glass or by introducing a bed of particles from the marker glass or by internally coating the longitudinal groove with the marker glass.
  • the cylindrical component or the bed or layer of the marker glass can also be fixed in the longitudinal groove by fusing.
  • the tube wall can contain a material that has a higher viscosity than the cladding glass, so that the bore does not completely collapse during the fiber drawing process and is retained as a cavity ("airline") in the finished multi-core fiber.
  • the recess ensures a positive fit between the marker element and the jacketed glass cylinder.
  • the marker element and the cladding glass cylinder can also be connected to one another in advance (ie: before the core rods are introduced into the core rod bores) by material bonding, for example by sintering together or fusing.
  • the marker glass fills the recess completely or partially.
  • the marker glass volume is dimensioned in such a way that the marker glass in the molten state fills the opening volume of the recess as completely as possible and ideally exactly. As a result, asymmetries in the fiber drawing process are avoided as far as possible.
  • the cross-sectional contours of the recess and the marker element do not have to match for this.
  • the recess preferably has a round bottom and the marker element has a round cross section adapted thereto with a slightly smaller radius.
  • the component ensemble created in this way includes the cladding glass cylinder, the cross rod, the marker element and at least two core rods.
  • the list designations (a) to (f) do not specify any order of the process steps.
  • the marker element is preferably attached to the jacketed glass cylinder.
  • the marker element benefits from its straightness and alignment; these properties are practically transferred to the marker element.
  • the attachment is based, for example, on frictional, material and/or positive locking between the filling rod and the marker element.
  • the marker element extends along the longitudinal axis of the jacketed glass cylinder and preferably over its entire length.
  • the marker element is preferably provided in the form of a cylindrical component or in the form of a layer or glass mass connected to the filler rod.
  • the at least one cylindrical component is, for example, a tube and preferably a rod.
  • the marker glass preferably differs from the cladding glass and any glass filling material in at least one physical and/or chemical property, the property being selected from: refractive index, color, fluorescence and/or specific glass density.
  • the property (or the properties) that distinguishes the marker element from the glasses of the component ensemble affects in particular the optical-visual appearance of the marker element and is preferably by means of a optical sensor detectable.
  • the glass composition of a marker glass can be based on quartz glass, just like the glass filling material, for example.
  • the refractive index of quartz glass can be changed by doping. For example, doping a marker quartz glass with fluorine lowers the refractive index compared to undoped quartz glass. An incorporation of carbon in the marker quartz glass can lead to a black discoloration. Doping the marker quartz glass with titanium causes a gray-blue color depending on the oxidation state. Doping the marker quartz glass with rare earth metals or germanium oxide is reflected in fluorescence at dopant-specific wavelengths.
  • the specific glass density of the marker element can be changed by pores and is reflected in a reduction in optical transparency compared to bubble-free glass.
  • the jacketed glass cylinder is preferably a hollow cylinder having a central bore.
  • Such hollow cylinders are obtained, for example, using the OVD process (Outside Vapor Deposition) after the deposition mandrel has been removed.
  • the production of cladding glass hollow cylinders using the OVD process is inexpensive compared to other production methods, especially compared to the VAD process (Vapor Phase Axial Deposition).
  • VAD process Vapor Phase Axial Deposition
  • the central bore mentioned above can remain. This can be completely or partially closed by means of a core rod or a glass rod containing another glass filler.
  • the semi-finished product according to the invention comprises a jacketed glass cylinder, the outer jacket surface of which has a recess, which extends in the direction of the cylinder's longitudinal axis, for receiving a marker element.
  • the recess preferably forms a longitudinal groove (longitudinal groove) on the outer lateral surface of the jacketed glass cylinder.
  • a longitudinal groove in the outer lateral surface is particularly easy to manufacture compared to a bore; for example by milling with a mechanical milling cutter or by laser ablation. On the other hand it is like this
  • the longitudinal groove produced is just as precise and straight as the cladding glass cylinder itself.
  • the depth or the opening width of the longitudinal groove can be kept almost arbitrarily small; for example both less than 15mm, preferably less than 10mm and most preferably less than 5mm.
  • the recess (longitudinal groove) is designed to accommodate a marker element with a small volume, which has a deviation in its axial alignment of less than 0.3 mm/m and accordingly forms correspondingly small and highly precise marker zones in the multi-core fiber obtained from the semi-finished product.
  • the jacketed glass cylinder is preferably a hollow cylinder having a central bore.
  • Such hollow cylinders are obtained, for example, using the OVD process (Outside Vapor Deposition) after the deposition mandrel has been removed.
  • the production of cladding glass hollow cylinders using the OVD process is inexpensive compared to other production methods, especially compared to the VAD process (Vapor Phase Axial Deposition).
  • VAD process Vapor Phase Axial Deposition
  • the central bore mentioned above can remain. This can be completely or partially closed by means of a core rod or a glass rod containing another glass filler.
  • the semi-finished product is intended for carrying out the method according to the invention and is suitable and designed for this.
  • the explanations relating to the jacketed glass cylinder in connection with the method according to the invention also apply to the semi-finished product and are hereby included.
  • the cladding glass cylinder is elongated and has a substantially cylindrical shape. There may be deviations from the cylindrical shape in the area of the front ends. It is designed as a solid cylinder or as a hollow cylinder. It contains a cladding glass that forms the cladding glass area.
  • the cladding glass consists, for example, of undoped quartz glass or it contains at least one dopant that lowers the refractive index of quartz glass. Fluorine and boron are dopants that can lower the refractive index of quartz glass.
  • the core rods contain a core glass that has a homogeneous or a non-homogeneous refractive index profile in the radial direction.
  • the core glass of each of the core rods forms a core glass area.
  • the core rods may include a region of core glass with a relatively high refractive index and at least one further region of another glass with a relatively low refractive index; for example a quartz glass that is doped with fluorine and/or chlorine.
  • the glass with the highest refractive index is usually in the central axis of the core rod. It consists, for example, of quartz glass to which at least one dopant has been added to increase the refractive index.
  • the core rod forms at least one signal core in which the signal to be transmitted is mainly transported.
  • the signal core may be adjacent to other lower refractive index glass regions that have also been provided by the core rod.
  • the marker element contains air and/or a marker material; in particular at least one marker glass.
  • the composition of the marker glass differs from that of the cladding glass and/or the density of the marker glass differs from that of the cladding glass.
  • the marker element is in the preform and in the component ensemble as component or as a layer or mass on a component and forms an optically detectable marker zone in the multi-core fiber.
  • the “component ensemble” includes the cladding glass cylinder with core rods inserted therein and the at least one marker element.
  • a "preform” is obtained, also referred to herein as a "consolidated preform”.
  • the assembly or (consolidated) preform is elongated into a "secondary preform” or directly into the multi-core fiber.
  • the component ensemble, the consolidated preform and the secondary preform are subsumed under the term "semi-finished product”.
  • Quartz glass is, for example, melted from naturally occurring SiO 2 raw material (natural quartz glass), or it is produced synthetically (synthetic quartz glass) or it consists of mixtures of these types of quartz glass.
  • Synthetic, transparent quartz glass is obtained, for example, by flame hydrolysis or oxidation of synthetically produced silicon compounds, by polycondensation of organic silicon compounds using the so-called sol-gel process, or by hydrolysis and precipitation of inorganic silicon compounds in a liquid.
  • fusion means that the components are fused to one another at a contact surface.
  • the fusion takes place by heating the components at least in the area of the contact surface using a heat source such as an oven, a burner or a laser.
  • the information relates to positions in the elongation process or in the fiber drawing process.
  • “Bottom” denotes the position in the pulling direction, "Up” the position opposite to the pulling direction.
  • bore denote holes with any internal geometry. They are produced, for example, by a drilling process, or they arise in that a layer of material is deposited on the outer lateral surface of a mandrel by a deposition process or a pressing process and the mandrel is then removed.
  • figure 1 shows schematically a cross section of a cylinder 1 made of a cladding glass, which serves as a base body for the production of a multi-core fiber.
  • the jacketed glass cylinder 1 consists of non-doped, synthetically produced quartz glass.
  • the quartz glass forms a cladding glass area 1a.
  • the jacketed glass cylinder 1 has a length of 1500mm and is adjusted to a nominal outside diameter of 200mm by cylindrical grinding.
  • a longitudinal groove 5 is produced on the cylinder outer shell 4 .
  • Four holes 3 are produced in a predetermined (here square) configuration by mechanical drilling in the direction of the cylinder longitudinal axis 2, which is shown in FIG figure 1 perpendicular to the plane of the sheet.
  • the holes 3 are used to hold core rods ( figure 2 ) and have a diameter of 24mm.
  • the holes 3 extend through the entire cylinder 1 (through holes).
  • the holes are designed as blind holes.
  • the longitudinal groove 5 milled into the cylinder outer jacket 4 extends over the entire length of the jacketed glass cylinder 1. It is semicircular in cross section with an opening width of 10 mm and a depth of 5 mm.
  • FIG 2 shows a component ensemble 10 made of cladding glass cylinder 1, core rods 7 and a marker rod 6 inserted into the longitudinal groove 5.
  • the marker rod 6 is also 1500 mm long and has a diameter of 3.5 mm. It consists of synthetically produced quartz glass that is doped with fluorine and is commercially available under the designation F320. Both the viscosity and the refractive index of the fluorine-doped quartz glass of the marker rod 6 are smaller than in the case of the undoped quartz glass from which the cylinder 1 consists.
  • the marker rod 6 is obtained by elongating a starting cylinder from the F320 quartz glass in a tool-free process.
  • the marker rod 6 inserted into the longitudinal groove 5 is fixed in the longitudinal groove 5 by selective heating using a burner.
  • four core rods 7 are produced from germanium-doped quartz glass with a length of approximately 1500 mm and an outer diameter of approximately 22 mm.
  • Known techniques are also suitable for this, for example the MCVD method (Modified Chemical Vapor Deposition).
  • figure 2 shows schematically, the core rods 7 inserted into the bores 3.
  • the core glass of the core rods 7 forms a core glass area 7a.
  • the lower end of the jacketed glass cylinder 1 equipped with the core rods 7 is then heated so that the annular gaps 8 collapse around the core rods 7 and the fluorine-doped quartz glass of the marker rod 6 melts and is distributed in the longitudinal groove 5 .
  • the glass volume of the former marker rod 6 is matched to the inner volume of the longitudinal groove 5 in such a way that the marker glass 11 just completely fills the longitudinal groove 6 .
  • figure 3 shows schematically the preform 20 consolidated in this way from the former ensemble components: cladding glass cylinder 1, core rods 7, marker rod 6, which forms the marker glass mass 11 in the preform. This is exposed on the outer shell of the cylinder 4 and on a line 12 running radially outwards from the center point, which does not belong to any axis of symmetry of the fiber design.
  • the consolidated preform 20 is then elongated into a secondary preform.
  • the preform 20 is held in an elongation device by means of a holder in the vertical alignment of the longitudinal axis 2 of the cylinder.
  • the secondary preform produced in this way is finally drawn into a multi-core fiber 20 in a drawing device in the usual way.
  • their cross section essentially corresponds to the cross section of figure 3 the consolidated preform 20 shown.
  • the former core rods 7 form signal cores extending along the longitudinal fiber axis; and the former marker glass mass 11 forms a marker zone on the cylindrical surface of the multi-core fiber.
  • the multi-core fiber is characterized by a particularly low fiber curl and a particularly good splicing behavior.
  • figure 5 shows schematically a cross section of a cladding glass hollow cylinder 41, which is produced in a known manner using the OVD method.
  • SiO 2 soot particles are formed by passing a high-purity SiO 2 starting material, for example silicon tetrachloride, through a deposition burner and a Burner flame is supplied, in which solid SiO 2 is formed therefrom. This is deposited from the gas phase in the form of fine SiO 2 soot particles on the outer surface of a cylindrical separating mandrel rotating about its longitudinal axis, with the deposition burner performing a reciprocating back and forth movement along the longitudinal axis of the separating mandrel.
  • a high-purity SiO 2 starting material for example silicon tetrachloride
  • SiO 2 soot body forms on the outer lateral surface of the separating mandrel. After completion of the separation process, the separation mandrel is removed so that a central inner bore 42 remains. The SiO 2 soot body is then vitrified in a furnace under vacuum, with the central 42 inner bore not collapsing, ie being retained.
  • the hollow cylinder 42 obtained in this way consists of non-doped, synthetically produced quartz glass. It has a length of 1500mm and is adjusted to an outer diameter of 200mm and an inner diameter of 42mm by cylindrical grinding. By mechanical drilling in the direction of the longitudinal axis 2, four further, evenly distributed, bores 3 with a diameter of 42 mm are produced around the central inner bore 42.
  • a longitudinal groove 5 is milled into the cylinder outer jacket 4, which extends over the entire length of the jacketed glass cylinder 41 and which is semicircular in cross section and has an opening width of 10 mm and a depth of 5 mm.
  • the cladding glass hollow cylinder 41 serves as a semi-finished product for the production of a multi-core fiber, with the central inner bore 42 of the cladding glass hollow cylinder 41 being filled with a filling rod made of the cladding glass or another glass material in the further course of this production process, or it is - as in this Exemplary embodiment - filled with a central core rod.
  • figure 4 shows schematically a using the cladding glass hollow cylinder 41 of figure 5 consolidated preform 40.
  • the marker stick is also 1500mm long and 3.5mm in diameter. It is obtained by elongating a starting cylinder from the F520 quartz glass in a tool-free process and has a smooth, damage-free surface created in the melt flow. It is characterized by high dimensional accuracy and straightness, so that it can be easily inserted into the longitudinal groove.
  • the marker stick inserted in the longitudinal groove is fixed in the longitudinal groove by heating it up at specific points using a burner.
  • the preform 40 consolidated in this way consists of the former ensemble components: cladding glass hollow cylinder 41, which forms the cladding glass area 1a, core rods, which form the core glass areas 7a, and marker rod, which forms the marker glass mass 11 in the preform 40. It is then elongated into a secondary preform, which is finally drawn into a multi-core fiber in a conventional manner in a drawing device.
  • the marker zone near the edge is particularly precise and has a small volume, so that the multi-core fiber is characterized by particularly low fiber curl and particularly good splicing behavior.

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EP22151954.9A 2022-01-18 2022-01-18 Procédé et préforme pour la fabrication d'une fibre multicoeurs Withdrawn EP4212488A1 (fr)

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EP22151954.9A EP4212488A1 (fr) 2022-01-18 2022-01-18 Procédé et préforme pour la fabrication d'une fibre multicoeurs
PCT/EP2023/050959 WO2023139049A1 (fr) 2022-01-18 2023-01-17 Procédé et produit semi-fini destinés à la production d'une fibre multicœur

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150284286A1 (en) 2014-04-08 2015-10-08 Corning Incorporated Method for making preforms and optical fibers
US20150307387A1 (en) 2014-04-25 2015-10-29 Corning Incorporated Method for forming optical fiber and preforms
US20160070058A1 (en) * 2013-12-18 2016-03-10 Sumitomo Electric Industries, Ltd. Multicore optical fiber and optical module
US20160347645A1 (en) * 2014-03-06 2016-12-01 Furukawa Electric Co., Ltd. Production method of optical fiber preform and production method of optical fiber
US9541707B2 (en) 2011-08-01 2017-01-10 Furukawa Electric Co., Ltd. Method for connecting multi-core fiber, multi-core fiber, and method for manufacturing multi-core fiber

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9541707B2 (en) 2011-08-01 2017-01-10 Furukawa Electric Co., Ltd. Method for connecting multi-core fiber, multi-core fiber, and method for manufacturing multi-core fiber
US20160070058A1 (en) * 2013-12-18 2016-03-10 Sumitomo Electric Industries, Ltd. Multicore optical fiber and optical module
US20160347645A1 (en) * 2014-03-06 2016-12-01 Furukawa Electric Co., Ltd. Production method of optical fiber preform and production method of optical fiber
US20150284286A1 (en) 2014-04-08 2015-10-08 Corning Incorporated Method for making preforms and optical fibers
US20150307387A1 (en) 2014-04-25 2015-10-29 Corning Incorporated Method for forming optical fiber and preforms

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